JPS6136336A - Production of powdery rubber - Google Patents

Abstract

PURPOSE:To obtain a powdery rubber having good dispersibility in asphalt and improved flocculation preventing property and fluidity in storage, by adding a synthetic resin emulsion to a powdery rubber containing a foaming agent dispersed therein. CONSTITUTION:An anionic or nonionic rubber latex is mixed with 0.1-10pts.wt., based on the dry weight of the above-mentioned rubber latex, anionic water-soluble high polymer, e.g. sodium alginate or sodium carboxymethyl cellulose, and 0.1-100pts.wt., based on the dry weight of the above-mentioned rubber latex, foaming agent, e.g. N,N'-dinitro-pentamethylenetetramine. The resultant mixture solution is then dropped and mixed in an aqueous solution containing 0.1-10pts. wt. cationic water-soluble high polymer or cationic surfactant, e.g. polyvinylpyridine, causing coacervation with the above-mentioned anionic water-soluble high polymer under acidic conditions under acidic conditions, and 1-30pts.wt. synthetic resin emulsion, e.g polystyrene, is added thereto. The resultant mixture is then dehydrated and dried.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is a book relating to a method for producing powdered rubber with excellent dispersibility in asphalt. The present invention relates to a method for producing powdered rubber in which a foaming agent is dispersed within the powdered rubber, which prevents agglomeration during storage and has improved fluidity.

[Conventional technology]

Powdered rubber has been used not only for its original purpose but also for purposes that take advantage of its powdery nature, unlike veil-like or chip-like rubber. For example, asphalt used for bridge pavement, rooftop construction, etc. is modified by adding rubber. As a method for modifying this asphalt, rubber latex containing about 50 parts of water is generally added. This method requires a water evaporation operation, but when powdered rubber is used, this operation is unnecessary and is economical. Furthermore, powdered rubber is used as an asphalt modifier because it is advantageous because it does not transport excess water in the rubber latex.

However, when powdered rubber is used as an asphalt modifier, although the asphalt properties improve to some extent, it has poor dispersion when mixed with asphalt.
A sufficient improvement in asphalt properties could not be achieved.

The present inventors have discovered that powdered rubber in which a foaming agent is dispersed in powdered rubber significantly improves the dispersibility in asphalt, and have previously completed a powdered rubber and a method for producing the same. However, due to its nature, rubber is sticky even at room temperature and has high elasticity, so even once it is made into pellets or powder, it usually sticks to each other and becomes blocks during transportation, storage, etc. It is.

[Problem that the invention seeks to solve]

The object of the present invention is, for example, to store 20 to 9
Powder containing an internal blowing agent dispersed in powdered rubber with industrially advantageous fluidity that maintains its powder form even under the load of 8 bags (approximately 48 g/cIIt) and during storage in the summer. K says that he will provide rubber.

Structure of the Invention [Means for Solving the Problems] As a result of extensive research aimed at providing a method for producing powdered rubber that overcomes these drawbacks, the present inventors have synthesized an aqueous dispersion of powdered rubber. The present invention was completed based on the discovery that powdered rubber added with a resin emulsion and dehydrated and dried prevents agglomeration during storage and significantly improves fluidity.

[Effect]

The method for producing powder rubber of the present invention, which prevents agglomeration during storage and has improved fluidity, has a foaming agent dispersed inside the powder rubber. mixing the molecules, and dropping the mixture under acidic conditions into an aqueous solution of a cationic water-soluble polymer or cationic surfactant that causes coacervation with the anionic water-soluble polymer under acidic conditions, This method is characterized in that a synthetic resin emulsion is then added and dehydrated and dried.

The rubber targeted in the present invention can be any rubber as long as it can be obtained as an anionic or nonionic latex, and natural rubber (NR) or a single conjugated diene compound such as isoprene, petadier/aa brene, etc. can be used. The polymers are polyisoprene rubber (KR), polybutadiene rubber (BRL polyisoprene rubber (OR), the above-mentioned conjugated diene compound, styrene, and acrylonitrile.

Styrene-butadiene rubber (EJBR), which is a copolymer with a vinyl compound such as vinyl pyridine, acrylic acid, methacrylic acid, alkyl acrylate, or alkyl methacrylate, and acrylonitrile-butadiene rubber (
NBR), vinylpyridine butadiene styrene rubber, methyl methacrylate butadiene rubber, methyl methacrylate butadiene rubber, etc., as well as ethylene, propylene,
Isobutylene isoprene rubber (AER), which is a copolymer of olefins such as isobutylene and a conjugated diene compound
etc.

Examples of anionic water-soluble polymers used in the present invention include natural products such as sodium alginate-Arabicum, carrageenan, agar, sodium carboxymethyl cellulose, polyvinyl sulfol copolymer, methyl methacrylate copolymer, crotonic acid- There are synthetic products such as vinyl acetate copolymer, styrene-maleic acid copolymer, cellulose acetate phthalate, and starch acetate phthalate. These water-soluble polymers are used in an amount of α1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on the dry weight of the rubber latex, and are usually mixed in the form of an aqueous solution. If it is less than 0.1 part by weight, the core cell page tanning will not be successful, and if it exceeds 10 parts by weight, it will cause side reactions and is economically meaningless.

As the blowing agent used in the present invention, rubber industry.

Resin industry 9 General products used in various industries such as the food industry can be used. Examples include %N, N'-dinitroso pentamethylene tetramine, azodicarbonamide, azobis imbutyronitrile benzene sulfonyl hydrazide, toluene sulfonyl hydrazide, and the like.

Although these blowing agents may be added to the rubber latex as they are, it is preferable to add them as an aqueous slurry.

A preferred method is to disperse the blowing agent in the form of fine particles as uniformly as possible in water using a domil, a centrifugal pump, a high-speed mixer, or the like. The foaming agent aqueous slurry concentration is 3 to 40 parts by weight, preferably 5 to 20 parts by weight. These blowing agents have a dry weight of rubber latex (relative to α1~1
00 parts by weight, preferably in the range of 1 to 50 parts by weight. If the blowing agent amount is less than [L1 part by weight, the mixing and dissolving effect will be small and the rubber will form aggregates in the asphalt. Furthermore, if the amount of the blowing agent exceeds 100 parts by weight, the foaming of the blowing agent will continue for a long time in the asphalt, and the mixing and dissolving operation will take a long time.

The anionic water-soluble polymer used in the present invention and the substance that causes core cell page number under acidic conditions include polyvinylpyridine, polybenzylaminoethyl cellulose,
Acidic polymers such as polydiethylaminoethylstyrene and polyvinylbenzylamine, dodecyltrimethylamine,
Acetic acid of higher amines such as coconut alkyldimethylamine, hardened tallow alkyldimethylamine, polyoxyethylene tallow alkylpropylene diamine, dodecyltriethanolamine, coconut alkylamine, dodecylamine, tallow alkylamine, cetylamine, stearylamine, hardened tallow alkylamine, etc. Examples include cationic surfactants such as salts, hydrochlorides, sulfates, dimethyl sulfates, nitrates, and quaternary ammonium salts. These substances are used in the form of an aqueous solution in an amount of α1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on the dry weight of the rubber latex.

In the present invention, first, a mixture of the rubber latex, a blowing agent, and an anionic water-soluble polymer is heated under acidic conditions to cause coacervation with the anionic water-soluble polymer at the cationic water-soluble polymer or ionic interface. By mixing the activator in an aqueous solution, the rubber can be separated into powder.

In order to effectively separate powders, there is a suitable ratio between the anionic water-soluble polymer and the substance that causes coacervation, but this can be easily selected through appropriate experiments. It is.

Powder separation can only occur under acidic conditions, and the pH of the powder separation system must be maintained at acidic S, preferably pH 5 or less. Acids used for this purpose include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as acetic acid, but there are no restrictions on the method of adding these acids. It is sufficient if it is maintained at .

This operation can be easily and well controlled by simply mixing each solution under stirring, and the rubber immediately separates into powder. In this case, it is affected by the amount of water in the solution or the strength of stirring, but it is not an important factor.
The suitable amount of water or stirring strength can be easily determined in each case by conducting appropriate experiments.

The synthetic resin emulsion is then added to the powdered rubber. The synthetic resin emulsion used herein refers to an emulsion in which synthetic resin particles having a glass transition temperature of 30° C. or higher are dispersed in an aqueous medium.

Such synthetic resin emulsions include polystyrene, polymethyl methacrylate, methyl methacrylate/methyl acrylate copolymer, polyvinyl chloride, vinyl chloride-vinylidene chloride copolymer, polyvinyl acetate, styrene-acrylonitrile, and polychlorotrichloroethylene. There are emulsions of fluororesin, etc.

These synthetic resin emulsions are added in an amount of 1 to 60 parts by weight, preferably 2 to 15 parts by weight, based on the dry weight of the rubber latex. When the amount of the synthetic resin is less than 1 part by weight, it is difficult to obtain sufficient effects and there is a tendency for blocks to form. 50 again
If it is used in excess of parts by weight, the properties as a rubber will be impaired, which is not preferable.

Through the above operations, the isolated powdered rubber containing a blowing agent dispersed inside the powdered rubber can be easily dehydrated using, for example, a centrifuge, and has fluidity or can be easily pulverized by a light pulverization operation. can. The material is then dried, but the drying method is not particularly limited, and methods such as ventilation drying, hot air drying, vacuum drying, and fluidized drying can be freely selected and used.

In order to obtain a dry powdered rubber having a uniform particle size, it is preferable to use a fluidized drying method or a flash drying method that allows drying in a state of motion.

〔Effect of the invention〕

The powdered rubber obtained by the method of the present invention has good dispersibility in asphalt, prevents agglomeration during storage, and has good fluidity, and is expected to expand the field of use and has great industrial and economic effects.

〔Example〕

Examples will be described below, but the invention is not limited thereto. In the examples, unless otherwise specified, parts represent weight.

In the present invention, the cohesiveness of the powdered rubber under load is approximately 1309 in the dry powder rubber in length and 6 (++s) in width.

Fill a box with a depth of 70 m, and add 9 bags to 20 and 8
Force equivalent to the load applied to the bottom of the bag stack, 4897 cd
The rubber powder was stored at 55°C for 24 hours under a load of 100°C, and then taken out from the storage and evaluated by the force required to break it and the particle size of the powdered rubber before and after storage.

Production example of rubber latex and synthetic resin emulsion used in the examples (4) Polychloroprene rubber latex (hereinafter abbreviated as PCR) In a nitrogen stream, rosin, potassium, soap and caustic soda (1
4 parts of formaldehyde-sodium naphthalene sulfonate condensate were dissolved in water, and then chloroprene monomer in which 12 parts of n-dodecyl mercap 2F #z6-di-t-butyl-p-cresol (111 parts) was dissolved was added. The mixture was emulsified, and polymerization was carried out at 40° C. while adding a 100% aqueous solution of potassium persulfate dropwise. Polymerization was stopped at 70% conversion,
Unreacted chloroprene monomer was distilled off to reduce the dry weight to 35
% PCR was obtained.

(Crocodile acrylonitrile-butadiene rubber latex (
(hereinafter abbreviated as NBR) High NBR (Product name [N11) 0115 manufactured by Zeon Corporation
71J) was adjusted to have a dry weight of 35% l/.

(C) Polybutadiene rubber latex (hereinafter abbreviated as BR) BR (manufactured by Japan Synthetic Rubber Company, product name [JSR0700J)
Adjusted so that the dry weight was 35 cm.

(D) Styrene-butadiene rubber latex (SD
(abbreviated as R) SBR (Product name: JEIR0561 manufactured by Japan Synthetic Company)
J) was adjusted to have a dry weight of 55 Yu.

((e) Polymethyl methacrylate emulsion (hereinafter abbreviated as PMMA) 7.5 parts of sodium alkylaryl polyoxyethylene sulfonate in 200 parts of water in a nitrogen stream.

175 parts of sodium dodecylbenzenesulfonate was dissolved, then 150 parts of methyl methacrylate was added, and the mixture was polymerized at 75°C using potassium persulfate as an initiator. The dry weight of the PMMA obtained was 40 inches.

(F!l, j-' polyvinyl chloride emulsion (hereinafter abbreviated as PvC) FVO (product name manufactured by Nippon Zeon Co., Ltd.)
5J) was used. Dry weight was 40 inches.

(G) Polystyrene emulsion (hereinafter abbreviated as PBt) 7.5 parts of sodium alkylaryl polyoxyethylene sulfonate in 100 parts of water in a nitrogen stream.

7 parts of sodium lauryl sulfate [1L] was dissolved, then 65 parts of styrene was added, and polymerization was carried out at 70°C using potassium persulfate as an initiator. The dry weight of the resulting pst was 40 inches.

Examples Examples 1 to 6 Using the combinations of reagents shown in Table 1, powdered rubber containing a foaming agent dispersed within the powdered rubber was produced. That is, 1.0509 g of a 1.050 g aqueous solution of rubber latex 3.0 OOIC anionic water-soluble polymer and 105 g of a blowing agent were added as a 20 g aqueous slurry, mixed until a homogeneous solution was obtained, and
The pH was adjusted to &5 by slowly adding an aqueous solution of acetic acid. Next, this mixed solution was poured into an aqueous α5 4.2009 solution containing 2 parts by weight of higher amine acetate at room temperature with stirring, and the rubber was immediately separated into powder.

The pEI after powder separation was 4.9.

Next, a synthetic resin emulsion was added in an amount of 5 parts by weight based on the dry weight of the rubber latex, and mixing was continued for about 10 minutes. After washing with a cotton cloth and dehydrating with a centrifuge, a wet powder rubber was obtained which could be easily powdered by hand.

Next, it was dried in a fluidized fluid dryer to obtain a powdered rubber having a uniform particle size as shown in Table 2. When these powdered rubbers were evaluated for cohesiveness after being stored under load at 55° C. for 24 hours, as shown in Table 2, they could be easily broken down with one hand, indicating that they were hardly agglomerated. Furthermore, the particle size after storage was almost unchanged from before storage, indicating that the properties as a powdered rubber were not impaired.

Comparative Examples 1 to 5 Examples 1 to 6 using the combinations of reagents shown in Table IK
A powdered rubber containing a blowing agent dispersed inside the powdered rubber was manufactured using the same procedure as described above. As shown in Table 2, when the obtained powdered rubber is stored under load at 55°C for 24 hours without adding a synthetic resin emulsion, it aggregates like a sponge after storage and does not break. It can be seen that even if it were possible to destroy it, it would not become the powder state before storage and would lose its properties as a powdered rubber.

Written Amendment of Procedures 1982 Fl 1J'] s [1 Manabu Shiga, Director General of the Patent Office, 1. Indication of the case, 1982 Special Request for Revision No. 157668, 2. Name of the invention, 3. Process for producing powder-fum. 3. Case of a person making an amendment. Relationship with Special Patent 8' (Applicant (contact address) 107 Toyo Sodatsu Kori Co., Ltd., 1-7-7 Akasaka, Minato-ku, Tokyo (Toso Building)) Patent Information Department Telephone number (585) 3311 4 Date of amendment order Voluntary N 7 6 Contents of amendment (1) At the bottom of page 6 of the specification, lines 8 to 4 "Can be used. There are..." to "Can be used and can be heated." It is preferable to use a blowing agent that decomposes the substance and generates gases such as carbon dioxide gas, nitrogen gas, and ammonia.Generally, the blowing agent is a combination of an inorganic blowing agent such as a weight or ammonium carbonate, and an organic blowing agent such as a nitroso compound, an azo compound, or a sulfonyl hydrazide. Although blowing agents can be broadly classified into blowing agents, organic blowing agents are more preferable for the present invention.

For example, nitroso compounds such as c, Nitrile, diazoaminobenzene, azo compounds such as barium azodicarboxylate, benzene,
Sulfonyl hydrazides include sulfonyl hydrazide, toluene sulfonyl hydrazide, diphenylsulfone-6,3'-disulfonyl hydrazide, and p,p'-oxybis(benzenesulfonyl hydrazide). ” he corrected.

Claims (1)

[Claims] A cationic water-soluble polymer or A method for producing powdered rubber, which comprises dropping and mixing a cationic surfactant into an aqueous solution under acidic conditions, then adding a synthetic resin emulsion, and dehydrating and drying.